This invention relates to a system of devices for shielding the operator from both atomized fluid and waste liquid generated during surgical procedures and associated methods of use.
Over the past 30 years, several ultrasonic tools have been invented which can be used to ablate or cut tissue in surgery. Such devices are disclosed by Wuchinich et al. in U.S. Pat. No. 4,223,676 and Idemoto et al. in U.S. Pat. No. 5,188,102.
In practice, these surgical devices include a blunt tip hollow probe that vibrates at frequencies between 20 kc and 100 kc, with amplitudes up to 300 microns or more. Such devices ablate tissue by either producing cavitation bubbles which implode and disrupt cells, tissue compression and relaxation stresses (sometimes called the jackhammer effect) or by other forces such as micro streaming of bubbles in the tissue matrix. The effect is that the tissue becomes liquefied and separated. It then becomes emulsified with an irrigant solution. The resulting emulsion is then aspirated from the site. Bulk excision of tissue is possible by applying the energy around and under an unwanted tissue mass such as a tumor to separate it from the surrounding structure. The surgeon can then lift the separated or excised tissue mass out using common tools such as forceps.
The probe or tube is excited by a transducer of either the piezoelectric or magnetostrictive type that transforms an alternating electrical signal within the frequencies indicated into a longitudinal or transverse vibration. When the probe is attached to the transducer, the two become a single element with series and parallel resonances. The designer will try to tailor the mechanical and electrical characteristics of these elements to provide the proper frequency of operation. Most of the time, the elements will have a long axis that is straight and has the tip truncated in a plane perpendicular to the long axis. This is done for simplicity and economic considerations. In almost all applications, whether medical or industrial, such an embodiment is practical and useful.
However, when the devices are used in open field surgery, particularly when the operative site is on the skin or slightly below, a side effect of the ultrasonic probe interaction with fluids becomes apparent. This is the ability of the ultrasonic vibrating tool to break up fluid and aerosol them such that the particles of fluid may be projected into the operating room atmosphere and either inhaled or otherwise contaminate people or surfaces.
The ability of ultrasonic probes to atomize fluid is well known. Many patents have been issued for just such hardware, such as U.S. Pat. No. 5,516,043, U.S. Pat. No. 4,153,201, U.S. Pat. No. 4,337,896, and U.S. Pat. No. 4,541,564, among many others. These devices have application in industry and medicine where it is desired to create fine particles of fluid and transport them to an airstream or onto a work surface. In operation, a fluid is introduced to the distal end of the vibrating probe. The frequency of vibration may be from 20 to 200 kHz or higher. The vibrating tip breaks the surface tension of the fluid and projects small amounts of fluid off the surface. The natural phenomenon of fluid to coalesce to a sphere in space creates small particles, which by their low mass and aerodynamic nature are easily suspended in air. Depending upon variables such as frequency of vibration, amplitude and liquid properties, ultrasonic atomizers can produce atomized particles with small diameters.
In the operating room, this atomization has caused concern since the fluids being atomized can contain blood, virus particles, bacteria or other objectionable constituents. This phenomenon of aerosoling contaminants is not limited to ultrasonic aspirators alone. Medical lasers can produce smoke when ablating tissue that contains viruses as well. It is well documented that the virus that causes vaginal warts may be present in laser smoke. When the smoke contacts operating room personnel, warts will appear on lips and other mucous membranes. Several inventions have been developed to combat this smoke problem. One such device is the smoke extractor unit. This is a vacuum pump, chemical filter and pickup hose assembly. In practice, the pickup funnel is placed near the operative sight. The air surrounding the site is sucked into the extractor funnel, similar to a vacuum cleaner effect. The smoke and objectionable elements are removed with the chemical filter. The air is then exhausted back into the room.
Although these devices work reasonably well with laser smoke, they do not provide solutions to all of the issues involved with ultrasonic surgery. The aerosols emitted by the ultrasonic probe are liquid in nature and will contaminate the chemical filter. The liquid will drip out of the filter, causing contamination that must be disinfected and cleansed. In addition, the air volume required for capture of the aerosols causes a draft or breeze around the wound, which could lead to contamination of the wound bed from other sources within the room.
Other devices have been proposed, such as in the U.S. Pat. No. 5,848,998 to Marasco, which discloses a closed bag placed around the limb with apertures for insertion of the ultrasound tool. The shield will trap the atomized fluids and contain the irrigant flow for collection later. In practice, these inventions have been shown to have some limitations. One problem is that the shield must be sized and shaped for the particular part of the body to be operated on. In addition, the apertures must be located over the wound. Since the shield is not totally elastic, it is often not possible to position the aperture in close proximity to the wound itself. Also, the shield becomes wet on the inside with atomized particles and becomes cloudy, which inhibits free vision of the operative site. In cases where suction is applied to the shield to aspirate the collected fluid, the shield will collapse on the limb, further impeding efficient treatment of the patient.
It is therefore desired to find a means to reduce the escape of aerosols into the general operating room atmosphere while not impeding the line of sight of the surgeon nor impeding convenient access to the wound.